Circumstances:
The pilot was conducting joy flights. The aircraft had just been refuelled. During a take-off, the helicopter reached a height of about 20 feet and an airspeed of approximately 30 knots when engine power decreased briefly, and rotor RPM decayed. The helicopter was over a dam at the time. While attempting to reach the nearby bank, the pilot turned downwind and overpitched the main rotors. The helicopter descended into 1.5 metres of fresh water. An engineering examination has disclosed that the right hand magneto had an intermittent fault and that the number three-cylinder lower spark plug lead had an intermittent short. The findings cannot be considered to be totally conclusive due to water immersion. However, it is considered probable that the engine power loss was an intermittent total spark loss on number three cylinder. This accident was not the subject of an on-scene investigation.
